Home-networking devices, such as gateways and set-top-boxes, needs to be compatible with more and more wireless standards. These standards are for example: WLAN (Wireless Local Area Network) operating in the 2.4 GHz and 5 GHz band, Bluetooth and RF4CE (Radio Frequency For Consumer Electronics) operating in the 2.4 GHz band, DECT (Digital Enhanced Cordless telecommunications) operating in the 1900 MHz band, and LTE (Long Term Evolution) operating in the UHF and L bands.
This demand of devices compatible with a plurality of wireless standards increases the number of requested antennas and subsequently increases the cost of devices. The demand of MIMO systems increases also the number of antennas. For a n-order MIMO system, n antennas are needed. In addition, the demand of radiation diversity for systems like RF4CE or DECT systems contributes also to this increase.
Different antenna architectures are possible for these multiband wireless systems. FIG. 1A to FIG. 1C illustrate three possible antenna architectures.
FIG. 1A shows a first antenna architecture comprising, for each requested band, a specific single band antenna and a specific filter. This solution is very costly since it requests a connector between each antenna and each filter.
FIG. 1B shows a second antenna architecture comprising a single wide band antenna and a specific filter for each requested band. In this architecture, the frequency bandwidth in which the antenna is well impedance-matched should cover all the frequency bands of the multiband system. A multiplexer is used in order to direct the signals towards the different filters and the associated transceivers. This solution is relatively cheap as it requests only one connector and one multiplexer. However, depending on the targeted frequency bandwidth, the design of this kind of antenna could be very tricky and could result in a trade-off solution between the size and the performances (return loss, gain, efficiency etc.). In addition, the wide band antenna can increase EMI issues because of its wide band gain.
FIG. 1C shows a third antenna architecture comprising a multi-band antenna and a specific filter for each requested band. With this kind of antenna, the antenna return loss response is multi-band. This means that the antenna is only well matched in the targeted frequency bands. This solution is low cost solution since it uses only one connector and one multiplexer.
The present invention has been devised with the foregoing in mind